Conventional dry-cleaning machines generally use petroleum solvents for washing. Examples of this type of dry-cleaning machines are disclosed in the Online Catalogue of SANYO Electric Techno Clean Co., Ltd., published on the WWW site located at: http://www.sanyo.co.jp/techno-c/clean/catalogue_top.html.
Recently, however, silicone solvents have been used more and more because, compared to petroleum solvents, they are less harmful to the environment, to the health of the worker using the machine, and to the health of the owner of the laundry article, who may suffer from solvent remaining in the laundry article.
Recently, water-repellent finishing is often performed within a cleaning process according to the request from the customer. By conventional dry-cleaning machines that continuously perform washing through drying, however, it is impossible to carry out the water-repellent finishing. The main reason for this is that water repellents used for that process consist of a small amount of a water-repellent resin mixed into a solvent. Therefore, spraying the water repellent onto laundry articles before the drying process will increase the amount of the solvent held in the laundry articles, which in turn increases the concentration of the solvent and makes the solvent highly inflammable during the drying process. With regard to the inflammability, silicone solvents, whose flash point is 77 degrees centigrade, is safer than petroleum solvents, whose the flash point is 53 degrees centigrade. Therefore, the switchover from petroleum solvents to silicone solvents provides a good reason to demand for the water-repellent finishing to be performed by dry-cleaning machines. Use of silicone solvents, however, cannot completely eliminate the possibility of explosion. Therefore it is still necessary to take appropriate measures to provide a high level of safety even when a silicone solvent is used in a dry-cleaning machine.
The basic construction of dry-cleaning machines using silicone solvents is the same as that of dry-cleaning machines using petroleum solvents. However, some points must be considered with respect to the difference in characteristics and features between the two solvents. For example, silicone solvents are far more costly than petroleum solvents, and accordingly increase the running cost. On the presumption that petroleum solvents are used, conventional dry-cleaning machines are constructed to allow a part of the solvent, volatilized during the drying process, to escape from the machine. In the case of using a silicone solvent, however, dry-cleaning machines should be constructed to recover as much solvent as possible to decrease the amount of the solvent to be replenished.
In the recovering and drying process, the water and solvent are condensed, liquefied and recovered as a mixture, which is then separated back into water and solvent with a water separation filter. The specific gravities of petroleum solvents are about 0.8, which significantly differs from that of water. With such a large difference in specific gravity, the water can be easily separated from the solvent. The specific gravities of silicone solvents, on the other hand, are about 0.95, which is considerably close to that of water. Though the small difference in specific gravity can still help with the separation of the water from the solvent, the separation takes such a long time that it cannot follow the cycle of the drying process of the machine. Therefore, it is necessary to use a new water separation filter capable of separating water from silicone solvents at a speed comparable to the operation cycle of the machine.
In view of the above problems, the first objective of the present invention is to provide a dry-cleaning machine capable of performing the water repellent finishing while ensuring a high level of safety. The second objective of the present invention is to provide a dry-cleaning machine capable of efficiently recovering the solvent to reduce the running cost. The third objective of the present invention is to provide a dry-cleaning machine capable of separately recovering the water and the solvent in a short time even in the case of using a silicone solvent or a similar solvent having a specific gravity close to that of water.